Power supply that provides an output voltage through an electrical connector

0001This application claims the benefit of U.S. Provisional Application No. 60/663,865, filed Mar. 21, 2005.

BACKGROUND OF THE INVENTION

0002This invention generally relates to a portable direct current power supply for a handheld electronic device. More particularly, this invention pertains to a direct current power supply for devices such as cellular phones.

0003The proliferation of portable battery powered devices, such as cellular telephones, has increased dramatically in the last several years and this trend is expected to continue. The phones typically use a rechargeable battery that is built into the phone to provide the needed power. The length of time that the battery powers the phone is dependent primarily upon the size of the battery and the number of energy consuming features built into the phone. In response to consumer demand, cell phone manufacturers incorporate into the phones features such as the ability to send and receive digital pictures and/or text messages. Unfortunately, the inclusion of these features usually places additional demands on the rechargeable batteries that power the cell phones. The net result is that the cell phones' run times become shorter and shorter due to the increased power demands. At the same time that the electrical demand placed on the battery is increasing, the size and weight of cell phones is decreasing in order to reduce the size of the phones. As the size of the cell phone is reduced, the size of the battery compartment built into the cell phone is also reduced. The existence of these two trends (i.e. increased electrical demand and reduced battery size) has caused many cell phone users to experience a failed telephone call or data transmission due to the depletion of their phone's battery at an inopportune moment. An additional trend that complicates resolving this problem is that most cell phones require a battery that has specific size and shape characteristics. In order to encourage consumers to purchase replacement batteries from the cell phone manufacturer, the cell phones are made with batteries that have unique shapes, locking mechanisms, voltage requirements, etc. Furthermore, the recharging port built into the cell phones limit the type of charger that can be connected to the cell phone. Collectively, these factors limit the consumer's ability to rapidly replace the depleted battery with another power supply.

0004Numerous attempts have been made to develop a suitable portable power supply for cellular telephones. For example, U.S. Pat. No. 6,127,801 discloses a power supply that includes a battery pack and a base unit which has bidirectional circuitry. The battery pack is made to snap into the base unit which is designed to be clipped onto the cellular telephone. Unfortunately, the battery pack and base unit tend to increase the size and weight of the cell phone, which is contrary to the consumer's desire, while also causing additional proliferation in the number of components the consumer needs to replace when the phone's battery is depleted. In another example, U.S. Pat. No. 6,709,784 discloses a unique battery pack that can be plugged into a cellular phone's contact to recharge the phone's built-in rechargeable battery and/or directly power the cell phone. This invention bundles the battery with the plug that allows the battery pack to be connected to the phone. Consequently, when the battery pack's battery is depleted the entire battery pack, including the plug, must be discarded which increases the consumer's cost.

0005Therefore, there exists a need for a portable direct current power supply that uses a commonly available battery that the consumer can readily insert into and remove from a reusable housing. The power supply needs to be lightweight, volume efficient and easily adaptable to a wide array of cell phones that utilize batteries of various shapes and sizes.

BRIEF SUMMARY OF THE INVENTION

0006The present invention provides a portable direct current power supply that can be used to supply an electric current to a handheld electronic device, such as a cellular telephone, that utilizes a battery that has a unique size and shape. The present invention is small, light weight, and inexpensive to operate.

0007According to a first aspect of the present invention, a portable electrochemical power supply includes a housing having an interior surface and an exterior surface, an electrical connector disposed through the housing, the connector having a first end accessible from the exterior surface. The power supply also includes a circuit board disposed within the housing. The circuit board is in electrical connection with both the electrochemical cell and the connector, receives an input voltage from the cell less than 1.90V and provides an output voltage through the connector greater than 3.00V. The housing includes at least two sections joined to one another a cavity adapted to removably receive an electrochemical cell.

0008According to another aspect of the invention, a process for providing an electric current to a battery powered device includes providing a battery powered device having at least one port physically and electrically configured to receive an electric current from an external power supply, selecting an electrochemical cell having a first terminal, a second terminal and an initial unaltered open circuit voltage less than 1.90 V, providing a housing for at least one circuit board and the electrochemical cell, disposing the cell inside the housing, securing a cover over the open end of the housing, providing an elongated electrically conductive connector, securing the elongated connector to the housing and to the device's port thereby establishing an electrical connection between the housing and the device, and allowing the assembled housing, elongated connector and device to remain connected while the circuit board receives an input voltage from the cell and provides an output voltage to the device. The input voltage is less than 1.90V and the output voltage is greater than 3.00V. The housing includes an open end, a sidewall and a closed end. The circuit board is capable of transforming an electrochemical cell's voltage from a first voltage to a second higher voltage. The housing also includes an electrically nonconductive first section defining the closed end of the housing and through which the electrical connector is disposed and an electrically conductive second section including the sidewall.

0009According to still another aspect, a portable battery powered power supply includes a first housing portion having a first end which includes a first opening and a second end, a second housing portion having a third and fourth ends and a battery receiving region disposed therebetween, a circuit board, and a power supply circuit carried by the circuit board. The power supply circuit includes an input which receives electrical energy from a first battery and an output which provides electrical energy to a battery powered device. The power supply also includes a first battery contact carried by the circuit board and which is in electrical communication with the input of the power supply circuit, an electrical connector carried by the circuit board and which is in electrical communication with the power supply output, and a second battery contact adapted to make electrical contact with a terminal located at the second end of the battery. The third end faces the first housing portion, the first battery contact is adapted to make electrical contact with a terminal located at a first end of a battery received in the battery receiving region, and the electrical connector is accessible to an exterior of the power supply through the first opening.

0010According to another aspect, a portable battery powered power supply is adapted to selectively receive first and second generally cylindrical batteries and supply electrical energy to an external portable battery powered device through an electrical connector. The power supply consists essentially of first, second, and third cover portions which lockingly engage so as to form a unitary assembly having a battery receiving region, a circuit board, a fourth cover portion, first and second user operable attachment members carried by the fourth cover portion and which are adapted to removably attach the fourth cover portion to the unitary assembly, and a mechanically resilient, electrically conductive member carried by the fourth cover portion. The circuit board carries power supply circuitry, the electrical connector, a first battery contact adapted to make electrical contact with a terminal located on a first end of the first battery, and a second battery contact adapted to make electrical contact with a terminal located at a first end of the second battery. The mechanically resilient, conductive member is adapted to provide an electrical connection between terminals located at a second end of the respective first and second batteries. The mechanically resilient, conductive member is in operative mechanical communication with the latch members.

0011According to still another aspect, a portable battery powered power supply includes a first polymeric cover portion, a second polymeric cover portion which lockingly engages the second cover portion so as to form a unitary assembly which includes a cavity adapted to receive a battery, a circuit board, and power supply circuitry carried by the circuit board. The power supply circuit includes an input which receives electrical energy from a battery and an output for providing electrical energy to an external device. The power supply also includes a first electrical connector carried by the circuit board and which is in electrical communication with the output of the power supply circuitry, a first battery contact carried by the circuit board and which is in electrical communication with the input of the power supply circuitry, a third polymeric cover portion which latchingly engages the unitary assembly so as to allow a user to selectively access the cavity, and a second battery contact carried by the third cover portion. The first electrical connector is adapted to provide a removable electrical connection to a corresponding external connector, the first battery contact is adapted to provide an electrical contact with a terminal located at a first end a battery received in the cavity, and the second battery contact is adapted to provide an electrical contact with a terminal located at a second end of the battery.

0012According to another aspect of the present invention, a method of assembling a battery powered power supply includes installing first and second human operable attaching members and a mechanically resilient, electrically conductive member in a first cover portion so that the conductive member urges the attaching members toward an interior surface of the first cover and provides a first battery contact. The method also includes snappingly attaching a second cover portion to a third cover portion to form a housing having first and second ends and a battery receiving region disposed therebetween, inserting a circuit board which carries an electrical connector, a second battery contact, and electrical circuitry which receives electrical energy from a battery and generates a power supply output for providing electrical energy to an external device in a fourth cover portion so that the electrical connector aligns with a first opening in the fourth cover portion. The method further includes snappingly attaching the fourth cover portion to the first end of the housing and using the attaching members to removably attach the first cover portion to the second end of the housing.

0013According to another aspect, a method of assembling a portable battery powered power supply includes placing a circuit board which carries an electrically conductive member, an electrical connector, a first battery contact, and electrical circuitry which receives electrical energy from a battery and generates a power supply output for providing electrical energy to an external device in a first cover portion so that the electrical connector aligns with a first opening in the first cover portion. The method also includes attaching the first cover portion to a second cover portion having first and second ends and a battery receiving region disposed therebetween so that the electrically conductive member makes an electrical contact with the first end of the first housing, and removably attaching a third cover portion which carries a second battery contact to the second end of the housing.

0014Still other aspects of the present invention will be understood by those skilled apart upon reading and understanding the appended description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

0015<figref idref="DRAWINGS">FIG. 1</figref> is an exploded cross-sectional view of a portable power supply;

0016<figref idref="DRAWINGS">FIG. 2</figref> is a cross-sectional view of an assembled portable power supply;

0017<figref idref="DRAWINGS">FIG. 3</figref> shows a perspective view of a portable power supply, flexible connector and cellular phone;

0018<figref idref="DRAWINGS">FIG. 4</figref> shows a flow chart of a process of this invention;

0019<figref idref="DRAWINGS">FIG. 5</figref> is a functional block diagram of an electronic circuit;

0020<figref idref="DRAWINGS">FIG. 6</figref> depicts the transfer function of an electronic circuit;

0021<figref idref="DRAWINGS">FIG. 7</figref> is a top front perspective view of a portable power supply;

0022<figref idref="DRAWINGS">FIG. 8</figref> is a top front perspective view of a portable power supply with a cover rendered transparent;

0023<figref idref="DRAWINGS">FIG. 9</figref> is a bottom front perspective view of a portable power supply with a cover rendered transparent;

0024<figref idref="DRAWINGS">FIG. 10</figref> is a perspective view of a printed circuit board and light pipe;

0025<figref idref="DRAWINGS">FIG. 11</figref> is a perspective view of the interior of a bottom cover;

0026<figref idref="DRAWINGS">FIG. 12</figref> is a perspective view of the exterior of a top cover;

0027<figref idref="DRAWINGS">FIG. 13</figref> depicts a cross section of a portion of a connector housing;

0028<figref idref="DRAWINGS">FIG. 14</figref> depicts steps in assembling a power supply.

DETAILED DESCRIPTION OF THE INVENTION

0029Referring now to the drawings and more particularly to <figref idref="DRAWINGS">FIG. 1</figref>, there is shown a cross-sectional view of a disassembled portable power supply <b>20</b> of this invention. The power supply generally comprises housing <b>22</b>, circuit board <b>24</b>, insulating ring <b>26</b>, and electrochemical cell <b>72</b>. Housing <b>22</b> includes an electrically nonconductive first section <b>28</b> and an electrically conductive second section <b>30</b> which can be further divided into first subsection <b>32</b> and second subsection <b>34</b>. First section <b>28</b> is made of an electrically nonconductive and transparent material that will allow the consumer to view components on the circuit board. Second section <b>30</b> is made of aluminum which is an electrically conductive material. First section <b>28</b> and second section <b>30</b> can be secured to one another. Circuit board <b>24</b>, commonly known as a printed circuit board (PCB), generally includes a thin electrically nonconductive disc shaped base member with a first planar surface <b>50</b> and a second planar surface <b>51</b>. Electronic components, such as resistors, diodes, voltage modifiers, etc. are printed and/or otherwise attached to either of the base member's planar surfaces. Secured to the first surface are a tubular metal contact <b>36</b> and a light emitting diode <b>53</b>. Secured to the circuit board's second surface is an arc shaped electrically conductive contact <b>99</b> positioned adjacent at least a portion of the board's perimeter. The arc shaped contact <b>99</b> on the second surface is in electrical contact with the electronic circuitry (not shown) secured to either the first planar surface and/or the second planar surface. A portion of the circuit board's tubular metal contact <b>36</b> extends through opening <b>38</b> in interior wall <b>40</b>. The diameter of opening <b>38</b> is larger than the outside diameter of the tubular metal contact's distal end <b>46</b> but smaller than the diameter of flange <b>42</b> which abuts the inside surface <b>44</b> of wall <b>40</b> thereby limiting the distance which the tubular contact can extend through the opening. Wall <b>40</b> is sufficiently recessed to prevent the distal end <b>46</b> of tubular contact <b>36</b> from extending beyond the plane defined by the rim <b>48</b> of nonconductive first section <b>28</b>. The insulating ring, which has an inner diameter that defines the size of opening <b>27</b> and an outer diameter, is made of an electrically nonconductive material. Ring <b>26</b> abuts the bottom <b>51</b> of circuit board <b>24</b> and ledge <b>52</b> in first subsection <b>32</b>. The leading edge <b>54</b> of first subsection <b>32</b> extends past ring <b>26</b> and makes an electrically conductive contact with the arc shaped electrically conductive contact <b>99</b> on the bottom surface of circuit board <b>24</b> when the power supply is assembled. First subsection <b>32</b> has an outer diameter <b>56</b>, an inner diameter <b>58</b>, a leading end <b>60</b> and a trailing end <b>62</b>. Both the leading and trailing ends are threaded to facilitate removably securing first subsection <b>32</b> to first section <b>28</b> and second subsection <b>34</b>, respectively. Second subsection <b>34</b>, also referred to herein as a cover, is a cup shaped component having a closed end <b>64</b> and a threaded opening <b>66</b> opposite the closed end. A coiled electrically conductive metal spring <b>68</b> is secured to the bottom inside surface <b>70</b> of cover <b>34</b>.

0030The assembled power supply disclosed in <figref idref="DRAWINGS">FIG. 2</figref> may be assembled as follows. Circuit board <b>24</b> is oriented and inserted into the housing's first section <b>28</b> so that the tubular metal contact projects through opening <b>38</b> in the first section's interior wall <b>40</b> until the tubular contact's flange <b>42</b> abuts the interior surface <b>44</b> of wall <b>40</b>. Insulating ring <b>26</b> is then inserted into the leading end <b>60</b> of the housing's first subsection <b>32</b>. The outer diameter of disc <b>26</b> is slightly larger than the first inside diameter <b>58</b> of first subsection <b>32</b> and slightly smaller than the inside diameter of ledge <b>52</b> thereby insuring that disc <b>26</b> rests upon ledge <b>52</b> and does not block the leading edge <b>54</b> of first subsection <b>32</b>. First section <b>28</b> is then secured to first subsection <b>32</b> by threading the first section onto the first subsection thereby trapping disc <b>26</b> and establishing an electrical path between the first subsection's leading edge <b>54</b> and the peripheral contact on the bottom surface <b>51</b> of circuit board <b>24</b>. To minimize the cost and volume of the power supply, the housing was designed to eliminate a separate wire or other electrical conductor that could have been used to complete the electrical circuit from the cell's second terminal to the circuit board. This was accomplished by constructing first subsection <b>32</b> and second subsection <b>34</b> of aluminum which is an electrically conductive material. Other electrochemically conductive materials, such as nickel plated steel, copper or brass could be used instead of aluminum. If desired, the housing could be made of an electrically nonconductive material, such as plastic, provided an electrically conductive path is provided between the cell's second terminal and the circuit board. The electrically conductive path could be a thin, elongated strip of brass secured to the interior surface of the nonconductive housing and which wraps around or otherwise terminates at the leading edge <b>54</b> of the housing so as to make electrical contact with the arc shaped contact <b>99</b> of the PCB. Electrochemical cell <b>72</b> is then inserted into cavity <b>74</b> so that the cell's first terminal <b>76</b> extends through opening <b>27</b> in insulating disc <b>26</b> and contacts a centrally located electrical contact on the bottom surface of circuit board <b>24</b>. The disc prevents electrical contact between the first terminal and other electronic components that may be located on the bottom of the circuit board. Second subsection <b>34</b>, also referred to herein as a cover, is then secured to the trailing end <b>62</b> of first subsection <b>32</b> by manually rotating the cover around the periphery of the first subsection's outer wall so that the threaded ridges <b>80</b> on the outer surface of the first subsection engage the grooves <b>82</b> in the inner surface of the cover. Spring <b>68</b> forces the cell toward the circuit board thereby insuring the establishment and maintenance of good physical contact between the cell and the circuit board while also providing an electrically conductive path between the cell's second terminal and the cover.

0031Secured to the circuit board are the components of an electronic circuit <b>300</b>. The components may be secured to the circuit board's first side <b>50</b>, which is the side of the circuit board furthest away from the electrochemical cell, or to the circuit board's second side <b>51</b>, which is located closest to the cell.

0032A first portion of the circuit functions as a sensing circuit and a second portion of the circuit functions as a boost circuit. The basic function of the sensing circuit is to detect the presence of a battery powered device to which the power supply is connected and then determine whether or not the electrochemical cell secured within the power supply's housing will be able to provide a current with sufficient amperage and voltage to operate the device and/or recharge a rechargeable battery that forms a part of the device. If one or more of the device's electrical characteristics that the sensing device can detect, such as electrical resistance, is not acceptable to the sensing circuit, the sensing circuit will not allow the boost circuit to supply power to the device. Similarly, if the sensing circuit determines that the cell's electrochemical capacity has been sufficiently depleted to prevent the cell from providing an adequate current to the boost circuit, then the sensing circuit will not allow the boost circuit to operate. In one embodiment, the sensing circuit can be made to attempt to detect the presence of a suitable device and electrochemical cell approximately two times per second. From the consumer's point of view, the power supply is always “on”. However, since the drain on the cell that powers the sensing circuit is very small the cell can power the sensing circuit for long periods of time before the cell must be replaced.

0033The function of the boost circuit is to transform the cell's voltage, which is also referred to herein as the boost circuit's input voltage, from a first voltage to a second higher voltage. Preferably, the boost circuit's input voltage, which is defined as the cell's closed circuit voltage prior to discharging the cell in any circuit that depletes more than one percent of the cell's theoretical electrochemical capacity, is below 1.90V. The boost circuit receives the cell's energy, which has a voltage below 1.90V, and transforms it to produce an output voltage greater than 3.00V which is the minimum voltage needed to power many commercially available cellular telephones. If desired, the boost circuit could be configured to transform the output voltage to a different voltage such as 3.60V. The boost circuit is not activated until the sensing circuit determines that the cell's output voltage and the device's electrical characteristics meet predefined criteria such as a minimum closed circuit voltage for the cell and a maximum electrical resistance for the device.

0034With reference to the functional block diagram of <figref idref="DRAWINGS">FIG. 5</figref>, the electronic circuit <b>300</b> is in operation operatively connected between the electrochemical cell <b>72</b> and a battery <b>310</b> which powers an electrical device <b>88</b> such as a cellular telephone.

0035The electronic circuit <b>300</b> is powered by the electrochemical cell <b>72</b>. The electronic circuit <b>300</b> converts the energy provided by the electrochemical cell <b>72</b> to a voltage and current level suitable for providing power to the electrical device <b>88</b>.

0036In one embodiment, the electronic circuit <b>300</b> receives input power from an alkaline AA cell having a nominal voltage of 1.5 volts direct current (VDC) and produces an output voltage greater than about 3.0 volts direct current (VDC). More particularly, the circuit <b>300</b> provides charge current to a lithium ion battery <b>310</b> having a nominal voltage of 3.6 volts direct current (VDC). The electronic circuit <b>300</b> includes a controller <b>306</b> operatively connected to charging/boost circuitry <b>307</b> which in turn provides electrical energy to the lithium ion battery <b>310</b>. Input sense circuitry <b>302</b> is operatively connected to the electrochemical cell <b>72</b> and provides the controller <b>306</b> with an indication of the voltage supplied by the cell <b>72</b>. Load sense circuitry <b>304</b> is operatively connected to the load <b>310</b> and provides the controller <b>306</b> with a signal indicative of the current drawn by the load <b>310</b>. A human readable indicator <b>308</b> such as one or more light emitting diodes (LEDs) indicates the status of the power supply.

0037An exemplary graph showing the relationship between the output current and voltage supplied to the lithium ion battery <b>310</b> and the input voltage supplied by the electrochemical cell <b>72</b> is shown in <figref idref="DRAWINGS">FIG. 6</figref>. Over a first range of voltages near the nominal 3.6 volt direct current (VDC) voltage of the lithium ion battery <b>310</b>, the circuit <b>300</b> functions as a current source to provide a substantially constant charging current to the battery <b>310</b>. As the battery <b>310</b> voltage increases with increasing battery charge, the current supplied to the battery <b>310</b> is reduced until the battery <b>310</b> is substantially charged.

0038With continuing reference to <figref idref="DRAWINGS">FIG. 5</figref>, the electronic circuit <b>300</b> also includes input sense circuitry <b>302</b> which senses the input voltage provided by the electrochemical cell <b>72</b>. Above a first threshold voltage, for example approximately 1.1 volts direct current (VDC), the current supplied by the charging circuitry <b>307</b> remains substantially constant as a function of input voltage. As the cell <b>72</b> voltage decreases, the current supplied by the charging circuitry <b>307</b> likewise decreases. As the cell <b>72</b> voltage decreases below a second threshold, for example approximately 0.6 volts direct current (VDC), the controller <b>306</b> enters an idle mode or low power mode in which the boost circuit <b>307</b> is disabled and the charging circuitry <b>307</b> no longer supplies power to the lithium ion battery <b>310</b>.

0039The load sensing circuitry <b>304</b> senses the presence of a load at the circuit's output. If no load is detected, the controller <b>306</b> enters an idle or low power mode in which the boost circuitry <b>307</b> is disabled so as to conserve energy in the cell <b>72</b>. If, on the other hand, the load sensing circuit <b>304</b> indicates the presence of a suitable load, the boost circuit is enabled, and the electronic circuitry <b>300</b> provides a recharging current to the battery <b>310</b>. The controller <b>306</b> causes the indicators <b>308</b> to flash to indicate that the device is providing power to the load.

0040In one embodiment, the electronic circuit <b>300</b> is implemented using the TEC103 integrated circuit available from Techtium Ltd. of Tel Aviv, Israel. Of course, other embodiments of the circuit can also be implemented.

0041While the above description has focused on recharging the lithium ion battery <b>310</b>, the electronic circuit <b>300</b> may also provide an additional or auxiliary power source while the electrical device <b>88</b> is operational, or may be used to power the device directly.

0042Other embodiments of the electronic circuit <b>300</b> may also be implemented. Thus, for example, the circuit may be configured to provide voltage and/or current levels suitable for charging battery technologies other than lithium ion. The circuit may be configured to provide a suitable voltage and/or current to directly power a load in the absence of a battery <b>310</b>. Moreover, one or both of the input and load sense functions may be omitted.

0043Shown in <figref idref="DRAWINGS">FIG. 3</figref> is an exploded view of the following three articles: a portable power supply <b>20</b> of this invention; an elongated, flexible, electrically conductive connector <b>86</b>; and a cellular telephone <b>88</b>. Power supply <b>20</b> includes a transparent first section <b>28</b> through which can be seen two light emitting diodes <b>53</b>; tubular metal contact <b>36</b> and circuit board <b>24</b>. Located between one end of tubular contact <b>36</b> and printed circuit board <b>24</b> is spring contact <b>92</b> which is electrically isolated from tubular contact <b>36</b>. Spring contact <b>92</b> is electrically connected to one of the electrochemical cell's terminals and tubular contact <b>36</b> is electrically connected with the cell's other terminal. Flexible connector <b>86</b> includes first connecting means <b>94</b> on one end thereof and second connecting means <b>96</b> on the opposite end thereof. The connecting means are electrical plugs that can be used to establish electrical connection between a power supply and a device. The two plugs are electrically connected and physically secured to one another by a flexible wire that includes a metal conductor coated by an electrically nonconductive material. First connecting means <b>94</b> includes an outer insulated portion <b>102</b>, a first conducting portion <b>104</b>, a second conducting portion <b>106</b> and an insulating sleeve <b>108</b>. First conducting portion <b>104</b> is a tubular metal contact that is designed to form an interference fit with the inside diameter of tubular contact <b>36</b>. Insulating sleeve <b>108</b> lines the inside surface of first portion <b>104</b> and extends slightly beyond the distal end of first portion <b>104</b> thereby forming an electrically insulated path through which second conducting portion <b>106</b> extends. When the consumer grasps outer insulated portion <b>102</b> and inserts first connecting means <b>94</b> into the power supply's tubular metal contact <b>36</b>, first conducting portion <b>104</b> establishes electrical contact with tubular contact <b>36</b> and second conducting portion <b>106</b> establishes electrical contact with spring <b>92</b>. Second conducting means <b>96</b> is sized to fit in the cavity defined by port <b>110</b> in cellular telephone <b>88</b>. Because manufacturers of cellular phones may use one of several different ports, and each port is uniquely sized relative to the other ports, the consumer needs to select a flexible electrically conductive connector that has a second connecting means that is properly configured to match the port in their phone. If a consumer needs to sequentially power two different cellular telephones with different size ports, such as could occur when the consumer exchanges their old cell phone for a new cell phone, the power supply is still usable provided a flexible connector that will fit the new phone is selected. When the flexible connector's first connecting means is plugged into the power supply's tubular contact and the second connecting means is plugged into the device's port, the power supply's sensing circuit detects the cellular phone and allows the power supply to send a current to the phone provided one or more predefined characteristics are detected by the sensing circuit.

0044As shown in <figref idref="DRAWINGS">FIG. 4</figref>, a process of this invention includes the following steps. In step <b>200</b>, providing a battery powered device. The device includes a port to which an electrically conductive connecting means can be secured. In step <b>202</b>, assembling a portable power supply. The power supply includes a housing having a removable electrochemical cell disposed therein. In step <b>204</b>, an elongated electrically conductive connector is provided. The connector has a first connecting means secured to one end and a second connecting means secured to the other end of the connector. Step <b>206</b> represents securing the first connecting means to the power supply and the second connecting means to the device's port. In step <b>208</b>, the device, elongated connector and power supply are allowed to remain connected while the printed circuit board receives an input voltage from the cell and provides an output voltage to the device wherein the input voltage is less than 1.90V and the output voltage is greater than 3.00V.

0045A preferred battery for use in a portable direct current power supply of this invention is a single primary cylindrical battery that incorporates a single anode that includes lithium, a single cathode that includes iron disulfide and a nonaqueous electrolyte. The preferred battery has a jellyroll construction wherein strips of the anode (lithium), cathode (iron disulfide) and separator are rolled to form a coil which is then inserted into the container that forms the body of the cell. Jellyroll cells are known to have high anode-to-cathode interfacial surface area which facilitates high rate discharge. In a preferred embodiment, at least 20 percent of the cell's theoretical electrochemical capacity is discharged at 1.40V or higher and the cell has an initial unaltered open circuit voltage between 1.50V and 1.90V. Other suitable cell chemistries include: (1) a primary cylindrical cell that incorporates zinc, an alkaline electrolyte and one or more electrochemically active materials selected from the group consisting of manganese dioxide, nickel oxyhydroxide and silver oxide; (2) a metal/air cell that incorporates zinc, an alkaline electrolyte and has air access port(s) and/or an air manager; (3) rechargeable cells that utilize an alkaline electrolyte and electrodes that include nickel and cadmium or nickel and a metal hydride; and (4) cells that utilize a zinc anode, manganese dioxide in the cathode and an acidic electrolyte. To accommodate commercially available cell sizes, the power supply's housing is made to define a cylindrical cavity that will accept a single electrochemical cell, also referred to herein as a battery, such as an R6 (AA), R03 (AAA), R14 (C) or R 20 (D) size battery. Because the power supply utilizes commonly available batteries, there is no need to purchase several uniquely shaped batteries to power several different devices owned by a consumer. The power supply of this invention allows the consumer to use a single power supply to sequentially power many different devices.

0046One of the issues that may need to be considered in the design of a power supply that includes an electrochemical cell is the management of heat that is generated when the cell is discharged. For example, when an R6 size battery that includes zinc, manganese dioxide and an alkaline electrolyte is continuously discharged at a one amp constant current drain rate, the exterior surface of the cell can heat up to 45° C. If the peripheral surface of the cell contacts the interior surface of the power supply's housing, heat will be conductively conveyed to and through the cell's housing. If the power supply is then picked up by an unsuspecting consumer, such as a child, the elevated temperature of the power supply's housing could cause the consumer to suddenly drop the power supply resulting in harm to the consumer and/or damage to the power supply and/or device. One way to safely manage the heat generated by the battery is to minimize the contact between the recently discharged cell and the interior surface of the housing, particularly the amount of contact between the interior surface of the housing's sidewall and the battery's circumferential surface. Preferably, contact between the cell's circumferential surface area and the sidewall of the housing is limited to less than 5% of the cell's circumferential surface area which would insure that at least 95% of the cell's circumferential surface area does not contact the interior surface of the housing. This can be accomplished by incorporating into the housing a mechanism that centers the cell in the cavity upon insertion of the cell and then keeps the cell centered in the cavity regardless of how the power supply is oriented by the consumer. For example, insulating disc <b>26</b> (see <figref idref="DRAWINGS">FIG. 1</figref>) could be made of a sufficiently thick material to allow for the formation of ridges and/or grooves in the bottom surface <b>51</b> thereof that would limit side-to-side movement of the cell's first terminal <b>76</b> thereby restricting lateral movement of the cell. Similarly, the interior bottom surface <b>70</b> of cover <b>34</b> could be contoured to engage ridges and/or recesses on the cell's second terminal <b>78</b> and thereby prevent lateral movement of the cell in the cavity. Another way to manage the transfer of heat from the cell to the power supply's housing is to insert a tubularly shaped thermal insulator between the cell and the interior surface of the housing's sidewall. The diameter of the tubularly shaped insulator would need to be greater than the diameter of the cell and less than the inside diameter of the housing. Alternatively, a thermally insulating material could be applied to the housing's exterior surface. Yet another way to manage heat transfer is to insure that the inside diameter of the housing is at least 5% larger than the outside diameter of the cell thereby insuring the existence of an air gap between the housing and the cell's circumferential surface area.

0047The housing of the power supply shown in <figref idref="DRAWINGS">FIG. 1</figref> could be made with one or more openings through the housing to facilitate the movement of gases, such as oxygen and/or hydrogen, into or out of the housing. Certain batteries, such as cylindrical batteries that include powered zinc, manganese dioxide and an alkaline electrolyte, are known to produce hydrogen gas during discharge. The gas slowly escapes through the battery's housing by permeating through the cell's seal assembly. Openings through the power supply's housing will allow the gas to escape thereby avoiding a dangerous buildup of hydrogen gas in the power supply's housing. Another reason to incorporate openings through the housing is to allow oxygen in the air to access the electrochemical cell if the cell is an air cell which uses the oxygen as one of the cell's reactants. The oxygen would flow through openings in the power supply's housing and then through the openings in the electrochemical cell's housing where the oxygen could react with the cell's other electrochemically active material to produce an electric current. The openings could also be used to dissipate the heat generated by the cell as it is discharged.

0048Because the power supply of the present invention is intended for use by consumers in their day-to-day activities when the device and power supply may be temporarily stored in a purse, briefcase or coat pocket, the total volume occupied by the power supply needs to be minimized. Thus the volume occupied by the housing should be minimized relative to the volume occupied by the electrochemical cell. Preferably, the volume of the electrochemical cell should be at least 85% of the total volume occupied by the power supply. More preferably, the volume of the electrochemical cell should be at least 90% of the total volume occupied by the power supply. To accomplish this objective, a power supply of this invention is preferably designed to include an electrochemical cell having an outer diameter that is no less than 95% of the inside diameter of the cavity into which the cell is inserted.

0049The operation of a preferred power supply of this invention will now be described. A primary (nonrechargeable) battery having a first terminal electrically connected to a single anode, a second terminal electrically connected to a single cathode, and an unaltered open circuit voltage below 1.90V, is inserted through an opening into a partially enclosed housing that includes a printed circuit board and an electrical connector disposed through the housing. A cover is secured over the opening thereby providing an electrically conductive path between the cell's second terminal and an electrically conductive portion of the housing that establishes an electrical connection with the printed circuit board. The printed circuit board includes a sensing circuit that detects the presence of a properly inserted cell having a minimum voltage. The printed circuit board further includes a light emitting diode that is illuminated for a brief period of time to signal the consumer that the power supply is operational. The consumer then secures one end of an elongated electrically conductive connector to the power supply's electrical connector that extends through the housing and the second end of the elongated connector is secured to a cellular telephone's charging port. The power supply's sensing circuit detects the presence of a cell phone that can be recharged by the power supply and then activates the printed circuit board's boost circuit which increases the cell's voltage from less than 1.90V to 3.00V or higher. The power supplied by the power supply is used to recharge the cell phone's rechargeable battery and/or to directly power the cell phone. The sensing circuit monitors the cell's voltage and reduces or stops the power supply's output if the cell's voltage falls below a predetermined minimum voltage. For example, if the cell's voltage drops below a first threshold voltage, such as 1.10V, then the power supply's output is reduced. When the cell's voltage drops below a second threshold voltage, such as 0.60V, then the power supply's output is reduced to 0.0V.

0050Turning now to <figref idref="DRAWINGS">FIG. 7</figref>, a portable power supply <b>700</b> has top <b>702</b>, bottom <b>704</b>, front <b>706</b>, rear <b>708</b>, and first <b>710</b> and second sides <b>712</b>. As the power supply <b>700</b> is readily portable, the foregoing descriptions are intended to provide a consistent frame of reference with which to describe the power supply itself <b>700</b> and do not necessarily correspond to the reference frame of a user or otherwise to the external environment. As illustrated in <figref idref="DRAWINGS">FIG. 7</figref>, the power supply <b>700</b> is adapted to receive two (2) AA size cells. Also as illustrated, the power supply <b>700</b> has exterior dimensions of 83.4 millimeters length×41 millimeters wide×22.8 millimeters deep and takes the shape of an ovoid having generally flattened front <b>706</b> and rear <b>708</b> surfaces.

0051The power supply <b>700</b> includes a front cover <b>714</b>, rear cover <b>716</b>, a top cover <b>718</b>, and a bottom cover <b>720</b> which may advantageously be molded or otherwise formed using a polymer such as acrylonitrile butadiene styrene (ABS). Accessible through an opening which is generally centered in the top surface of the top cover <b>718</b> is an electrical connector <b>722</b> such as a female jack. A first human readable status indicator <b>724</b><i>a </i>is visible on the first side <b>710</b> of the top cover <b>718</b>. A corresponding second human readable status indicator <b>724</b><i>b </i>(see <figref idref="DRAWINGS">FIG. 9</figref>) is likewise visible on the second side <b>712</b>. A first latch <b>726</b><i>a </i>is located at the front <b>706</b> of the bottom cover <b>720</b>. A corresponding second latch <b>726</b><i>b </i>(again not visible in the perspective view of <figref idref="DRAWINGS">FIG. 7</figref>) is likewise located at the rear <b>708</b> of the bottom cover <b>720</b>.

0052<figref idref="DRAWINGS">FIGS. 8 and 9</figref> depict respective top front and bottom front perspective view of the portable power supply <b>700</b> with the front cover <b>714</b> rendered transparent for ease of illustration. The portable power supply <b>700</b> includes a battery receiving region <b>802</b> adapted to receive first and second generally cylindrical batteries. The rear cover <b>716</b> includes front facing, generally arcuate battery supports <b>806</b>. The front cover <b>714</b> contains similar, rear facing supports.

0053Protrusions <b>808</b> and recesses <b>810</b> disposed at the periphery of the rear cover <b>716</b> snappingly engage corresponding recesses and protrusions disposed at the periphery of the front cover <b>714</b>. More particularly, the clips and recesses are configured to facilitate assembly of the cover portions <b>714</b>, <b>718</b> into a unitary assembly but to resist ready disassembly by a user.

0054With additional reference to <figref idref="DRAWINGS">FIG. 11</figref>, the bottom cover <b>720</b> is removably attached to the power supply <b>700</b> so as allow a user to insert and remove the batteries. The bottom cover <b>720</b> carries the latches <b>726</b><i>a</i>, <b>726</b><i>b</i>, which are preferably identical, and the contact member <b>820</b>.

0055The latches <b>726</b><i>a</i>, <b>726</b><i>b </i>include user operable actuating portions <b>812</b><i>a</i>, <b>812</b><i>b </i>which are accessible through respective material free regions in the bottom cover <b>720</b>. As illustrated, the actuating portions <b>812</b><i>a</i>, <b>812</b><i>b </i>are substantially flush with the outer surface of the cover <b>720</b>. The latches <b>726</b><i>a</i>, <b>726</b><i>b </i>also include shoulder portions <b>1102</b><i>a</i>, <b>1102</b><i>b </i>having a dimension greater than that of the material free regions and which aid in retaining the latches <b>726</b><i>a</i>, <b>726</b><i>b </i>in position inside the cover bottom cover <b>720</b>.

0056The latches <b>726</b><i>a</i>, <b>726</b><i>b </i>also include cover engaging portions <b>814</b><i>a</i>, <b>814</b><i>b </i>which extend upwardly from the bottom cover <b>720</b>. The cover engaging portions <b>814</b><i>a</i>, <b>814</b><i>b </i>include recesses <b>816</b><i>a</i>, <b>816</b><i>b</i>, material free regions, catches, or the like which engage corresponding protrusions disposed in the inner surface of the front <b>714</b> and rear <b>716</b> covers. The respective protrusions have generally curved or wedge shaped profiles so that the height of the protrusions is relatively lower near the bottom of the respective covers and relatively higher near the top. As will be appreciated, such an arrangement facilitates the assembly of the bottom cover <b>720</b> to the front <b>714</b> and rear <b>716</b> covers but prevents ready disassembly unless the actuating portions <b>812</b><i>a</i>, <b>812</b><i>b </i>are depressed. The cover engaging portion <b>814</b><i>a</i>, <b>814</b><i>b </i>may also be configured to provide a protrusion which engages a corresponding recess or latch portions on the covers <b>714</b>, <b>716</b>.

0057The contact member <b>820</b> is fabricated from an electrically conductive, resilient material such as AISI 302 chromium nickel stainless steel. The contact member <b>820</b> is supported by a boss <b>822</b> which extends generally inwardly from the bottom inner surface of the bottom cover. A post <b>824</b> extends through a corresponding aperture in the contact member <b>820</b> so as to aid in positioning the contact member <b>820</b>. The post <b>824</b> may be heat staked or otherwise deformed so as to hold the contact member <b>820</b> in place. Other fastening techniques, such as a split post which snappingly engages the aperture, mechanical fasteners such as screws, adhesives, and/or interference fits are also contemplated.

0058The contact member <b>820</b> includes tabs <b>826</b><i>a</i>, <b>826</b><i>b </i>which engage corresponding slots or recesses in the inner portion of the latches <b>726</b><i>a</i>, <b>726</b><i>b</i>. The resilient nature of the contact member <b>820</b> tends to urge the latches <b>726</b><i>a</i>, <b>726</b><i>b </i>outwardly toward the bottom cover <b>720</b> until their respective shoulders <b>1102</b><i>a</i>, <b>1102</b><i>b </i>contact the inner surface thereof. The contact member <b>820</b> also includes first <b>828</b><i>a </i>and second <b>828</b><i>b </i>battery contacts which provide electrical connections to the terminals of batteries inserted in the battery receiving region <b>802</b>. The resilient nature of the contact member aids in providing a reliable electrical connection with batteries installed in the battery receiving region <b>802</b>.

0059As illustrated, the bottom cover <b>720</b> and associated components have rotational symmetry so that the contact member <b>820</b> may be installed in the bottom cover in either of two (2) 180° rotationally opposed positions; the cover latches <b>726</b><i>a</i>, <b>726</b><i>b </i>are interchangeable. Moreover, the bottom cover <b>720</b> may be likewise installed on the power supply in either of two (2) 180° rotationally opposed positions. A particular advantage of such a configuration is that assembly of and installation of the bottom cover <b>720</b> on the power supply <b>700</b> is simplified.

0060Returning now to <figref idref="DRAWINGS">FIGS. 8 and 9</figref> and with additional reference to <figref idref="DRAWINGS">FIG. 10</figref>, the top cover <b>718</b> includes first <b>902</b><i>a </i>and second <b>902</b><i>b </i>attaching members which snappingly engage the rear <b>716</b> and front <b>714</b> covers, respectively. The attaching members <b>902</b><i>a</i>, <b>902</b><i>b </i>are preferably keyed so that the top cover <b>718</b> cannot be installed in the incorrect orientation. More particularly, the first attaching member <b>902</b><i>a </i>includes a generally square aperture which is adapted to engage a correspondingly shaped protrusion <b>904</b><i>a </i>on the inner surface of the rear cover <b>712</b>. The second attaching member <b>902</b><i>b </i>likewise includes a generally circular aperture which is adapted to engage a correspondingly shaped protrusion on the inner surface of the front cover <b>714</b>. The respective protrusions <b>904</b> have generally wedge shaped profiles so that the height of the protrusions is relatively lower near the top of the respective covers and relatively higher near the bottom. As will be appreciated, such an arrangement facilitates the assembly of the top cover <b>718</b> to the front <b>714</b> and rear <b>716</b> covers but prevents ready disassembly by the user or otherwise.

0061A PCB <b>908</b> is carried by the top cover <b>718</b>. Disposed on a first side <b>912</b> of the PCB <b>908</b> are first and second battery contacts <b>906</b><i>a</i>, <b>906</b><i>b </i>which are adapted to make electrical contact with the respective terminals of batteries inserted in the battery receiving region <b>802</b>. Battery polarity members <b>910</b>, which extend from the inner surfaces of the front <b>714</b> and rear <b>716</b> covers, prevent the battery located nearer the first side <b>710</b> from being inserted with the improper polarity. More particularly polarity members <b>910</b> associated with each of the front and rear covers cooperate to form an aperture <b>998</b> of a size which allows the positive terminal of a desired size battery (AA in the illustrated embodiment) to protrude through the aperture <b>998</b> so as to contact the first battery terminal <b>906</b><i>a</i>. The aperture <b>998</b> has a dimension smaller than the outer diameter of the desired size battery so that the negative terminal cannot make such a contact.

0062The PCB <b>908</b> also carries power supply circuitry which converts the energy supplied by the batteries to the desired voltage and/or current levels at the power supply output. In one implementation, the power supply circuitry may function substantially as described above in connection with the circuit board <b>24</b> and the circuitry <b>300</b>. As illustrated in connection with <figref idref="DRAWINGS">FIGS. 7-11</figref>, however, the batteries are connected electrically in series. Consequently, the power supply circuit input voltage is ordinarily twice that provided to the circuitry of circuit board <b>24</b> such that the operation of the circuitry <b>300</b> would be adjusted accordingly. One consequence of such an arrangement is that the power supply <b>700</b> may advantageously be used to supply GSM mobile phones and other electrical appliances having relatively higher power requirements than can be effectively supplied by only a single battery.

0063<figref idref="DRAWINGS">FIG. 10</figref> depicts the second side <b>914</b> of the PCB <b>908</b>, the connector <b>722</b>, light sources <b>1001</b><i>a</i>, <b>1001</b><i>b </i>such as light emitting diodes (LEDs), and a light pipe <b>1002</b>. The connector <b>722</b>, which is electrically connected to the output of the power supply circuit, is carried on the second side <b>914</b> of the PCB <b>908</b>. The connector <b>722</b> is positioned to align with a corresponding opening in the top cover <b>724</b> when the PCB <b>908</b> is installed in the power supply <b>700</b> so that the connector is accessible from the exterior thereof. Keys <b>1008</b><i>a</i>, <b>1008</b><i>b</i>, which engage corresponding slots in the inner surface of the top cover <b>718</b>, prevent the PCB <b>908</b> from being installed in the incorrect orientation.

0064As illustrated, the connector <b>722</b> also includes a generally tubular or cylindrical portion <b>1098</b> which passes though a material free region of the light pipe <b>1002</b>. The exterior of the light pipe <b>1002</b>, which is fabricated from polycarbonate or other suitable material, has generally bow or arcuate shape which generally conforms to the shape of the top cover <b>718</b> so that the light pipe may be inserted therein. The exterior surface of the light pipe <b>1002</b> includes grooves or slots <b>1004</b> which engage corresponding bosses which protrude inwardly from the inner surface of the top cover <b>718</b> so as to aid in properly positioning the light pipe <b>1002</b>.

0065The light sources <b>1001</b><i>a</i>, <b>1001</b><i>b</i>, which are electrically connected to the power supply circuit so as to provide an indication of the circuit status, are positioned so that, when the PCB <b>908</b> and the light pipe <b>1002</b> are installed in power supply, the light sources <b>1001</b><i>a</i>, <b>1001</b><i>b </i>are in optical communication with corresponding light receiving portions <b>1006</b><i>a</i>, <b>1006</b><i>b </i>of the light pipe <b>1002</b>. The light pipe <b>1002</b> further aligns with a light transmissive or material free region of the top cover <b>718</b> so as to provide the status indicators <b>724</b><i>a</i>, <b>724</b><i>b </i>which are visible therethrough. Additionally, some or all of the annular portion <b>1096</b> of the light pipe <b>1002</b> may be disposed so as to be visible between the cylindrical portion <b>1098</b> of the connector <b>722</b> and the corresponding material free region of the top cover <b>718</b>. Such an arrangement can be used to provide an additional human readable indication at the top of the power supply <b>700</b>. As illustrated, the top cover <b>718</b> and light pipe <b>1002</b> have rotational symmetry so that the light pipe <b>1002</b> may be installed in the bottom cover in either of two (2) 180° rotationally opposed positions

0066An alternative implementation of the top cover <b>718</b> which facilitates the use of a rotationally locking external connector is illustrated in <figref idref="DRAWINGS">FIG. 12</figref>. A described above, the top cover <b>718</b> includes an aperture <b>1202</b> which aligns with and provides access to the connector. As shown in <figref idref="DRAWINGS">FIG. 12</figref>, however, the cover includes 180° opposed shelf or lip portions <b>104</b><i>a</i>, <b>1204</b><i>b </i>located at or near the top surface of the top cover <b>718</b> at which the aperture <b>1202</b> has a relatively smaller diameter. Stated another way, the cover also includes 180° opposed material free regions <b>1206</b><i>a</i>, <b>1206</b><i>b </i>located at or near the top surface of the top cover <b>718</b> at which the aperture has a relatively larger diameter. Additional lips or shelves <b>1208</b><i>a</i>, <b>1208</b><i>b </i>which restrict the aperture to a smaller diameter are disposed below the material free regions <b>1206</b><i>a</i>, <b>1206</b><i>b. </i>

0067A portion of the housing of a corresponding external connector has the cross section shown in <figref idref="DRAWINGS">FIG. 13</figref>. The housing includes lips or shelves <b>1302</b><i>a</i>, <b>1302</b><i>b </i>which are sized to fit through the material free regions <b>1206</b><i>a</i>, <b>1206</b><i>b</i>. The location and depth of lips <b>1302</b><i>a</i>, <b>1302</b><i>b </i>are selected so that the connector may be inserted in the aperture <b>102</b> and rotated so as to prevent the external connector from being removed from the power supply <b>700</b>. Though illustrated to provide a 90° rotationally locking connector, the aperture and external connector may readily configured to provide 180° or other desired locking actions. Such an arrangement may likewise be implemented in connection with cover <b>28</b>.

0068In one embodiment, the front <b>714</b> and rear <b>716</b> covers and the latches <b>726</b> are provided in first color, while the top <b>718</b> and bottom covers <b>720</b> are provided in a second color. Logos, instructions, additional decorative features or other similar items may also be provided on the outer surface of the housings, for example through additional molded plastic pieces suitably fastened thereto. The top cover <b>718</b> especially may also be rendered translucent or transparent.

0069Still other variations are possible. For example, the power supply <b>700</b> may be configured to receive AAA, C, D, or other sized batteries. The power supply may also be configured to accept four (4) or more batteries, or also only a single battery, provided that an electrically conductive path is provided between the cell's second terminal and the PCB <b>908</b>.

0070Assembly of the power supply will now be described in relation to <figref idref="DRAWINGS">FIG. 14</figref>. At <b>1402</b>, the front <b>714</b> and rear covers <b>716</b> are attached to form a housing body. In the illustrated embodiment, the covers are snapped together such that the protrusions <b>808</b> and recesses <b>810</b> engage.

0071At <b>1404</b>, the light pipe <b>1002</b> and PCB <b>908</b> are inserted in the top cover <b>718</b>. Stated another way, the top cover is placed over the light pipe <b>1002</b> and PCB <b>908</b>. Note that the light pipe may be installed in either of two 180° opposed positions. The PCB, however, is keyed and may be inserted in only a single rotational position.

0072At <b>1408</b>, the top cover <b>718</b> is attached to the housing body. In the illustrated embodiment, the pieces are snapped together such that the attaching members <b>902</b> engage their corresponding protrusions <b>904</b>. Note that the top cover <b>718</b> and the housing body can be attached in only a single rotational position.

0073At <b>1406</b>, the latches <b>726</b><i>a</i>, <b>726</b><i>b </i>and the contact member <b>820</b> are installed in the bottom cover <b>720</b>. The post <b>824</b> may be heat staked or otherwise deformed as desired.

0074At <b>1410</b>, the batteries may optionally be inserted in the battery receiving region <b>802</b>. The polarity members <b>910</b> prevent the negative terminal of an improperly inserted battery from making electrical contact with the battery contact <b>906</b><i>a. </i>

0075At <b>1412</b>, the bottom cover <b>720</b> is attached to the housing body. Note that the bottom cover <b>720</b> may be installed in either of two 180° opposed positions.

0076The lower cover <b>720</b> may be removed by depressing the actuating portions <b>812</b><i>a</i>, <b>812</b><i>b </i>of the latches <b>726</b><i>a</i>, <b>726</b><i>b </i>until the engaging portions <b>814</b><i>a</i>, <b>814</b><i>b </i>disengage from their respective protrusions and moving the lower cover <b>720</b> away from the remainder of the housing. The batteries are then removed from the battery receiving region through the resultant opening.

0077The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and are not intended to limit the scope of the invention, which is defined by the following claims as interpreted according to the principles of patent law, including the Doctrine of Equivalents.